The present invention relates to an inputting device and an electronic instrument such as a mobile communication terminal using this inputting device and an inputting method thereof, in particular, in which an operating section, which is displaced about in the horizontal and vertical directions for the plane being almost parallel to the surface of the cabinet of the electronic instrument, is provided, and the displacement of the operating section, in the slanting direction in the plane being almost parallel to the surface of the cabinet of the electronic instrument, is detected.